The Harvard Adult ACTU has several clinical centers for trials of promising drugs and drug strategies in the treatment of HIV infection or its complications. Main sites include the Massachusetts General Hospital (MGH), Beth Israel Deaconess Medical Center (BIDMC), and Boston Medical Center (BMC). An ancillary site will be the Brigham and Women's Hospital (BWH). This collaborative group draws from a wide patient catchment area in Massachusetts and throughout New England, including all socio-economic groups. Both sexes are represented and there is a wide diversity of racial and ethnic groups included in studies. All adult risk groups participate, and the number of under-represented and minority population participants has risen steadily in recent years. Studies are conducted on antiretroviral agents, and drugs active against opportunistic pathogens. Studies also are conducted on the pathogenesis of HIV infections, and on the effects of treatment strategies on the natural history of infection. Studies of the metabolic complications of HIV infection and its therapy also are underway. Individuals are studied at all stages of infection, and the current application proposes to extend these studies and to broaden the involvement of under-represented populations in HIV clinical trials. The Harvard Adult ACTU has made contributions to existing knowledge concerning the pathogenesis and therapy of HIV infection, and has contributed to the Scientific Agenda and leadership of the existing ACTG. Harvard has participated in the ACTG Quality Control program since its inception and is conducting critical studies on viral resistance and quantitation, and immunopathogenesis. This Unit plans to expand these research efforts within the framework of the ACTG Advanced Technology Laboratory Program.